As known, a communication network comprises a plurality of nodes connected by paths transporting data flows related to the provision of services to users of the network. Exemplary transmission technologies for communication networks are SDH/Sonet, Ethernet, WDM/DWDM (Wavelength Division Multiplexing/Dense Wavelength Division Multiplexing), IP (Internet Protocol), MPLS (Multi-Protocol Label Switching).
The systems and apparatuses implementing the connectivity between the nodes of the communication network based on any network transmission technology according to protocols belonging to layers 1 to 3 (i.e. from the physical layer to the network layer) of the ISO-OSI protocol stack (e.g. physical links, transmitters, receivers, routers, switches, etc.) are generally referred to as network resources.
The provision of services over a communication network is implemented by using IT (Information Technology) systems and apparatuses, such as computation units (e.g. CPUs), storage units or disks, I/O units, and so on. These systems and apparatuses are typically referred to as IT resources. These IT resources may be co-located with the network resources in the nodes of the communication network or, alternatively, they may be stand-alone systems and apparatuses.
Recovery mechanisms are known for managing a failure affecting a network resource, such as a link of the communication network (e.g. a fiber cut in a WDM network). These mechanisms allow the network to continue operating in the presence of the failure and, in particular, to continue transporting the data flows (and, therefore, to provide the services transported by such data flows) at their respective service level.
EP 1 473 887 discloses a system and method for implementing a shared protection scheme under a scenario of multiple failures in an optical network. In one embodiment of the invention, a working path between an ingress node and an egress node is computed responsive to a connection request received in the network. One or more backup paths are computed between the ingress and egress nodes, which are activatable upon a failure condition associated with the working path or the backup paths. The backup paths may be based on link and/or node disjointedness, as well as resource-based cost constraints.
EP 1 931 113 discloses a network device that load-balances network traffic among a set of network servers based on electrical power consumption of the network servers.
Lai, et al. “RFC3386: Network Hierarchy and multilayer survivability”, 7 Nov. 2002, XP002239553, discloses a set of interoperable survivability approaches in packet and non-packet networks.